code: def export_constant_pad() -> None:
      node = onnx.helper.make_node(
          "Pad",
          inputs=["x", "pads", "value"],
          outputs=["y"],
          mode="constant",
      )
      x = np.random.randn(1, 3, 4, 5).astype(np.float32)
      pads = np.array([0, 0, 1, 3, 0, 0, 2, 4]).astype(
          np.int64
      )  # pad order [x1_begin, x2_begin, ..., x1_end, x2_end, ...]
      value = np.float32(1.2)
      y = pad_impl(x, pads, "constant", 1.2)
  
      expect(
          node,
          inputs=[x, pads, value],
          outputs=[y],
          name="test_constant_pad",
      )
  
file_path: onnx/onnx/backend/test/case/node/pad.py
imports: import numpy
  import onnx
  from onnx.backend.test.case.base import Base
  from onnx.backend.test.case.node import expect
label_desc: Use image node_id 1 for calling the Pad obj's underlying member method code with example usage: obj.export_constant_pad() without return types